Control system for a vehicle braking system

Abstract

Aspects of the present invention relate to a control system (100), a vehicle (1), a method and computer readable instructions. The control system comprises one or more processors (120) collectively co

Description

16 09^5 TECHNICAL FIELD 5 The present disclosure relates to a control system for neutral gear selection on gradients. Aspects of the invention relate to a control system, a vehicle, a method and computer readable instructions. BACKGROUND It is known to provide a vehicle with a powertrain having multiple drive modes by which the torque transfer to 10 the wheels can be modified by the driver using a drive mode selector device. In automatic transmission vehicles, the powertrain is generally operable in one or more drive modes including: a forward drive mode ‘D’, a reverse drive mode ‘R’, a neutral drive mode ‘N’ and a park drive mode ‘P’. These drive modes can be selected by the driver using a drive mode selector, typically in the form of a lever, switch and / or rotary selector. In manual transmission vehicles, the powertrain is generally operable in number of drive modes including: a 15 reverse drive mode ‘R’, a neutral drive mode ‘N’, and multiple forward drive modes (1st, 2nd, 3rd...) which are typically selected by the driver using a drive mode selector in the form of a gear lever. With either type of transmission, it is possible for the driver to inadvertently select the neutral drive mode ‘N’ without realising. As will be understood, torque is not transferred to the wheels by the powertrain when the neutral drive mode ‘N’ is selected. This can result in expected vehicle behaviour. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a control system for controlling a braking system of a 25 vehicle, a vehicle, a method and computer readable instructions as claimed in the appended claims. According to an aspect of the invention there is provided a control system for controlling a braking system of a vehicle. The control system comprising one or more processors collectively configured to: receive at least one input parameter comprising: 30 a drive mode signal indicating a selected drive mode of the vehicle; in dependence on the at least one input parameter, identify if a condition is satisfied, wherein the condition requires at least that: the selected drive mode is a neutral drive mode; and in response to identifying that the condition is satisfied: output a braking torque request signal 35 for the braking system to request a braking torque from the braking system; and modify the braking torque request signal to increase the braking torque from the braking system during a taper-on period. In this manner, the control system can act automatically to slow or stop the vehicle, if it is moving, or resist movement if the vehicle is already at rest. This can give the driver more time to take corrective action, such 40 as selecting a different drive mode and / or applying the brake, if the driver deems it necessary to do so. 16 09^5 The drive mode may comprise at least a forward mode and a neutral mode. The drive mode may further comprise a reverse mode. The forward mode may comprise one forward mode, ora plurality of forward modes, for example each having a different gear ratio. 5 Drivers of vehicles can, on occasion, inadvertently put the vehicle into a neutral mode when undertaking low speed manoeuvres. For example, when parking a car, the driver could select a neutral gearshift position instead of a drive gearshift position (the forward drive mode) when the driver wishes to move the vehicle forward after a reverse portion of the parking manoeuvre has been completed in a reverse gearshift position (or vice versa). The neutral position is located between the drive and reverse positions on an automatic 10 gearshift. As a result, drivers who are unfamiliar with automatic vehicles may enter neutral and therefore the neutral drive mode by mistake. Similarly, fora manual gearshift vehicle, the neutral position is generally located between the forward gears and reverse gear(s), if the driver does not properly engage the forward gear, then the vehicle will remain in a neutral gearshift position. 15 In such cases, the vehicle driver may not have realised that they are in an incorrect gearshift position (that is a neutral position when they intended to be in a forward gear or reverse gear). If the vehicle is currently moving or on a gradient, then the vehicle could continue moving. Likewise, if the vehicle was initially stationary then the vehicle could begin moving under its own weight if located on a gradient. The control system advantageously requests a mitigating braking torque to stop or slow the vehicle. The braking torque is a torque applied by the brakes to arrest motion of a wheel. For example, where the brake is a brake calliper, the braking torque is generated by pressure applied by the calliper to a brake disc. In another example, where the brake is an eddy current brake, the braking torque is generated by the induction of eddy currents and resistance to those currents. 25 Alternatively, or optionally, in response to identifying that the condition is satisfied the one or more processors may output a braking force request signal to request a braking force instead of a braking torque request signal. Alternatively, or optionally, in response to identifying that the condition is satisfied the one or more processors 30 may output a braking pressure request signal to request a braking pressure instead of a braking torque request signal. The control system comprises one or more controllers collectively comprising at least one electronic processor having an electrical input for receiving an input signal; and at least one memory device electrically coupled to 35 the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon so as to: receive at least one input parameter comprising: a drive mode signal indicating a selected drive mode of the vehicle; 40 in dependence on the at least one input parameter, identify if a condition is satisfied, wherein the condition requires at least that: 16 09^5 the selected drive mode is a neutral drive mode; and in response to identifying that the condition is satisfied: output a braking torque request signal to the braking system to request a braking torque from the braking system; and modify the braking torque request signal to increase the braking torque from the braking system during a taper-on period. 5 By tapering the braking torque there is a more gradual application of torque rather than a step change braking torque application. This gradual increase in braking torque means that the vehicle may come to a more gradual stop rather than an abrupt stop, this can give more time for the driver of the vehicle to take corrective action, for example, complete the gear shift and put the vehicle in the forward or reverse drive mode as applicable. 10 Optionally, the taper on period is between 0.1 seconds and 3.0 seconds. The taper on period may be greater than 0.2 second, greater than 0.5 second, or greater than 1 second. The taper on period may be 1.5 seconds. In an embodiment, the at least one input parameter further includes a vehicle speed signal indicative of a 15 vehicle speed and / or a gradient signal indicative of a gradient of a surface on which the vehicle is supported. Optionally, the condition further requires one or more of: that the vehicle speed is above a minimum speed threshold; that the vehicle speed is below a maximum speed threshold; and that the gradient of the surface on which the vehicle is support has a magnitude which is greater than a gradient threshold. When the condition requires that the vehicle speed is above a minimum speed threshold, the control system does not request that the braking torque be made if the vehicle speed is less than or equal to the minimum 25 speed threshold. In such situations, the processors collectively identify that the condition is not satisfied and so the braking system is not requested to generate the braking torque by the torque request signal. This can avoid unnecessary intervention by the control system in certain scenarios, such as where the vehicle is at rest or a low speed (1-2 kph) and therefore no braking torque is required to moderate the vehicle speed. In such an example, once the vehicle speed decreases below the minimum speed threshold, the control system 30 recognises that the braking torque is not required and reduces or stops the braking torque requested from the braking system. When the condition requires that the vehicle speed is below a maximum speed threshold, the control system does not request that the braking torque be made if the vehicle speed is greater than or equal to the maximum 35 speed threshold. In such situations, the processors collectively identify that the condition is not satisfied and so the braking system is not requested to generate the braking torque by the torque request signal. This can avoid unnecessary intervention by the control system in certain scenarios, such as where the vehicle is being towed (which typically requires the vehicle to be in neutral) and travelling at relatively high speed, for example on a motorway or freeway. In such examples, once the vehicle speed exceeds the maximum speed threshold, 40 the control system recognises that the braking torque is not desirable and reduces or stops the braking torque requested from the braking system. 16 09^5 Where the condition requires both the minimum and maximum speed thresholds, the control system only requests the braking torque when the vehicle is operating in a defined speed range between the two speed thresholds. 5 When the condition requires that the vehicle is supported on a surface having a gradient with a magnitude which is less than a gradient threshold, i.e. where the vehicle is on a flat or relatively low gradient, then the control system does not request the braking torque. This can avoid the need for unnecessary interventions by the braking system when the vehicle is on the flat or on a gentle slope, since at low gradients the driver will 10 generally have more time to react without control system intervention than for medium-to-high gradients (e.g. greater than 5% gradient) where the vehicle may accelerate more quickly under its own weight. The at least one input parameter may further comprise a vehicle operating mode signal indicative of a current operating mode of the vehicle. The condition may further require identifying that the current operating mode 15 corresponds to one or more of a set of predefined vehicle operating modes. This enables the control system to output the braking torque request only when the vehicle is operated is certain vehicle operating modes and to avoid requesting braking torque in other vehicle operating modes. This can help to avoid the braking torque being applied when the vehicle is in a vehicle operating mode in which braking is not desired, such as when the vehicle is being towed or moving through a car wash, for example. The set of predefined vehicle operating modes may include a single pedal operating mode in which acceleration and braking functions are requested through a single pedal, typically the accelerator or “gas” pedal. Optionally, the condition requires that the vehicle speed is above the first speed threshold, and wherein the minimum speed threshold is zero. 25 Optionally, the condition requires that the vehicle speed is below the maximum speed threshold, and wherein the second speed threshold is 20 to 60 kph. Optionally, the condition requires that the gradient of the surface on which the vehicle is supported has a 30 magnitude which is greater than a gradient threshold, and wherein the gradient threshold is 1 %. Optionally, the braking torque request signal comprises a braking torque demand indicative of the braking torque requested from the braking system; and wherein the braking torque demand is dependent upon at least one of the vehicle speed and the 35 gradient of the surface on which the vehicle is support. With this arrangement, for certain driving conditions, the braking torque demand will be different when compared to other driving conditions. For example, where the road is steep and the vehicle is travelling at a first vehicle speed there may be a first value of the braking torque demand. In comparison when the vehicle is 40 traveling at the same vehicle speed but at a different, less steep gradient, the braking torque demand may be at a second value which is different to, e.g. lower than, the first value. 16 09^5 Optionally, the braking torque demand varies linearly in relation to one or both of the vehicle speed and the gradient of the surface on which the vehicle is supported. 5 By linearly relating the braking torque demand to one or both of the vehicle speed and the road gradient, the torque demand can be varied in dependence upon the current road conditions and speeds. The relationship between the braking torque demand and the vehicle speed and road gradient can be calculated by the one or more processors based on appropriate formulae. Alternatively, the input parameters 10 may comprise a look-up table defining the braking torque demand as a function of the road gradient and the vehicle speed. The one or more processors may be configured to select the braking torque demand from the look-up table based on the vehicle speed and the road gradient. The control system may further comprise at least one memory on which the look-up table is stored. The one 15 or more processors may be configured to access the at least one memory and read the look-up table stored thereon to identify the braking torque demand from said look-up table. Optionally, the one or more processors are collectively configured to, in response to identifying that the condition is no longersatisfied, modify the braking torque request signal to reduce the braking torque requested from the braking system. By tapering the braking torque there is a more gradual application of torque rather than a step change braking torque application. This gradual increase in braking torque means that the vehicle may come to a more gradual stop rather than an abrupt stop, this can give more time for the driver of the vehicle to take corrective action, 25 for example, complete the gear shift and put the vehicle in the forward or reverse mode as applicable. The braking torque request signal may be modified such that the braking torque requested is reduced gradually, or “tapered-off’. By reducing the braking torque gradually, abrupt or unexpected acceleration of the vehicle can be avoided. 30 The one or more processors may be collectively configured to calculate the modified braking torque in dependence upon the input parameters. For example, a reduction in the vehicle speed and / or road gradient can result in a reduction in the requested braking torque. 35 The modified braking torque may be determined by the one or more processors by providing a look-up table of modified braking torque demands paired with vehicle speeds and gradients the control system can quickly find the required modified braking torque to be utilised. Different modified braking torque demand values can be provided for a number of different values of vehicle speed or vehicle gradient enabling greater control of the braking potential of the vehicle for different driving scenarios. The reduced braking torque requested from 40 the braking system may be pre-calibrated. 16 09^5 The control system may further comprise at least one memory on which the look-up table is stored. The one or more processors may be configured to access the at least one memory and read the look-up table stored thereon to identify the modified braking torque demand from said look-up table. 5 In an embodiment, the one or more processors are collectively configured to, in response to identifying that the condition is no longer satisfied, modify or stop the braking torque request signal to reduce or stop the braking torque requested from the braking system. Once the vehicle has been arrested and no longer moving the braking torque may no longer be required as 10 the vehicle has been moved from the neutral drive mode to a different drive mode such as a forward or reverse drive mode or a parking mode. The at least one input parameter may further comprise a vehicle state signal indicating whether the vehicle is in an active state or an inactive state. The condition may further require that the vehicle is in the active state. 15 The vehicle usage signal is used to identify conditions whereby the logic can be employed or where other control system logic should take preference. For example, where the vehicle usage signal indicates that the vehicle is in an inactive state (for example if the driver side door is open), it may be beneficial for braking torque to be applied by alternative means - such as the parking brake - rather than by the control system. This can help to avoid multiple conflicting or confusing signals to be sent to the braking system(s) from different control systems. It can also enable braking torque to be applied more aggressively by a different control means to bring the vehicle more rapidly to a complete stop (e.g. by automatically applying the parking brake). The vehicle usage signal may comprise a vehicle power mode signal that indicates a current power mode of 25 the vehicle. In the vehicle power mode, the vehicle is turned on and, in a state, ready to move. The power mode is a vehicle driving mode. The vehicle driving mode may be one or both of: a transmission operating mode, and a driving operating mode comprising one or more sub-system modes indicating an operation of one or more vehicle sub-systems. The vehicle power mode may be a towing mode indicating that the vehicle is in a mode suitable for being towed by a second vehicle. The vehicle usage signal may comprise on or more of: 30 a door open signal indicating if one or more doors of the vehicle are open; a driver seat belt signal indicating if the driver seat belt is fastened; a driver seat empty signal indicating if the driver seat is occupied; and a vehicle power mode signal indicating a current power mode of the vehicle. The braking system may be a foundation braking system or a regenerative braking system, or the braking 35 system may comprise a foundation braking system and a regenerative braking system. According to a yet another aspect a vehicle is provided. The vehicle comprising the control system of any of any previous aspect. 40 According to a further aspect, there is provided a method for controlling a braking system of a vehicle. The method comprising: receiving at least one input parameter comprising: a drive mode signal indicating a selected drive mode of the vehicle; in dependence on the at least one input parameter, identifying if a condition is satisfied, wherein the condition requires at least that: 5 the selected drive mode is a neutral drive mode; and in response to identifying that the condition is satisfied: output a braking torque request signal for the braking system to request a braking torque from the braking system; and modify the braking torque request signal to increase the braking torque from the braking system during a taper-on period. 10 The method may further comprise any of the additional steps found in any control system of the control system aspect, or system of the system aspect, or vehicle of the vehicle aspect. According to a still further aspect, there is provided computer readable instructions which, when executed by a computer, are arranged to perform a method according to the previous aspect. Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in anyway and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS 25 One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a vehicle in accordance with an embodiment of the invention; Figure 2 shows a schematic diagram of the vehicle of Figure 1; Figure 3 shows a schematic diagram of a control system in accordance with an embodiment of the 30 invention; Figure 4 shows a flow chart in accordance with an embodiment of the invention; Figure 5 shows a flow chart in accordance with an embodiment of the invention; Figure 6 shows a flow chart in accordance with an embodiment of the invention; and Figure 7 shows a graph of braking pressure against time according to an embodiment of the invention. 35 DETAILED DESCRIPTION A vehicle 1, in accordance with an embodiment of the present invention may be a passenger vehicle, as shown in Figure 1, also referred to as a passenger car or as an automobile. In other examples, embodiments of the invention can be implemented for other applications, such as commercial vehicles, vans or the like. 40 Figure 2 schematically illustrates an example of at least part of a powertrain of the vehicle 1 with wheels 34. 16 09^5 16 09 25 As shown in Figure 2, a control system 100 in accordance with an embodiment of the present invention is installed in the vehicle 1. The control system 100 is shown in more detail in Figure 3 and is described further below with reference to the accompanying drawings. The control system 100 is suitable for controlling a braking system 60 of a vehicle 1 using at least one prime mover 26 (alternatively known as an actuator or 5 torque source). In this example, the vehicle 1 powertrain comprises a propulsion system 22 comprising the at least one prime mover 26. The prime mover 26 may be an internal combustion engine ‘ICE’ or an electric traction motor. Alternatively, the vehicle 1 may comprise a plurality of prime movers 26. Where a plurality of prime movers 26 are provided they may be one or more ICEs and an electric traction motor, or a plurality of electric traction 10 motors. The prime mover(s) 26 are selectively operable for the purpose of providing drive torque for accelerating the vehicle 1. In alternative configurations with two prime movers 26, the first prime mover 26 may provide drive to a front axle and the second prime mover 26 provides drive to a rear axle, or vice versa. Where the at least one prime mover 26 comprises an electric traction motor arranged to convert electrical 15 energy into kinetic energy (in the form of mechanical torque) it may also be arranged to convert kinetic energy into electrical energy. The electric traction motor 26 may be an alternating current induction motor or a permanent magnet motor, or another type of suitable electric machine. The electric traction motor 26 is a traction motor configured to enable at least an electric mode comprising electric-only driving. That is, the electric traction motor 26 can drive the vehicle 1 by itself (without additional torque provided by a second torque source such as an engine). Another term for the electric traction motor 26 is an electric drive unit (EDU). In order to store electrical energy for the electric traction motor 26, the vehicle 1 comprises an electrical energy storage means. The electrical energy storage means can be a traction battery 28. The traction battery provides a nominal voltage required by electrical power users such as the electric traction motor 26. The traction battery may be a high voltage battery. The traction battery may have a voltage and capacity to support electric only 25 driving for sustained distances. The traction battery may have a capacity of several kilowatt-hours, to maximise range. The capacity may be in the tens of kilowatt-hours, or even over a hundred kilowatt-hours. Although the traction battery 28 is described as one entity, the function of the traction battery could be implemented using a plurality of small traction batteries in different locations on the vehicle 1. An inverter 30 may be provided to convert between the DC output of the traction battery and the AC input required for the electric machine 26, 30 and vice versa. The vehicle 1 comprises a transmission system 10 comprising a transmission 12, such as a single-speed gear reduction unit. The transmission system 10 is connected to the prime mover 26. The transmission 12 may be an automatic transmission comprising a fluid torque convertor or a manual transmission comprising a plurality of selectable gears. A transmission output shaft 20 from the transmission 12 is connected to a final set of gears 35 32, such as a pinion gear meshed with a ring gear, to transfer torque to the wheel axles and thus to vehicle wheels 34. The braking system 60 is shown schematically in Figure 2 by a dashed line 60. The braking system 60 comprises brakes 62. The brakes 62 are foundation brakes. It will be appreciated that foundation brakes 8 16 09 25 include any braking system which decelerates the vehicle by converting kinetic energy of the vehicle into heat, as opposed to a regenerative brake, such as may be provided by an electric machine. Examples of foundation brakes are friction brakes such as drum brakes or disc brakes 62. Disc brakes 62 comprise a brake disc and a calliper. In order to arrest movement of a vehicle 1 it will be appreciated that this means, in the example of 5 disc brakes 62, that the application of a pressure from the calliper to the brake discs is used to slow vehicle 1 as is known in the art. Foundation brakes may comprise eddy current brakes in addition to other brakes. The brake system 60 also comprises regenerative braking which brakes the vehicle by the wheels driving the electric motor that in this mode serves as a generator, converting the kinetic energy of motion into electrical energy. This electrical energy may then be stored in the traction battery to add battery charge from a braking 10 event. The vehicle further comprises the control system 100 for controlling the braking system 60. The control system 100 is shown located as part of the propulsion system 22, however the control system 100 may be located at any suitable location within the vehicle, for example within the transmission system 10 or as part of the braking system 60. The control system 100 is electrically connected to one or more sub-systems of 15 the vehicle 1 including the braking system 60 to enable communication between the control system 100 and other components of the vehicle 1, such as a brake controller. The vehicle 1 has a number of drive modes which are selectable via a drive mode selector 70. The drive mode selector may be any suitable selector as is known in the art, such as a gesture sensor based drive mode selector, a lever or a rotary selector. For example, the drive mode selector may be the drive mode selector as described in WO2018130378A1, which describes a DRIVE MODE SELECTOR FOR A DRIVETRAIN, VEHICLE COMPRISING SUCH A DRIVE MODE SELECTOR, AND A METHOD OF SELECTING A DRIVE MODE OF A DRIVETRAIN, this document is incorporated herein by reference. For reasons of clarity and to aid teaching the invention, the drive mode selector 70 shown in Figure 2 is a lever 70, however it is envisioned that the drive mode selector 70 may be any previously described device or device 25 known with the art suitable for selection of a drive mode. The drive mode selector 70 comprises a controller (not shown). The controller may be a separate computer, such as a microprocessor, or may be a software module running on a computer, such as a microprocessor, that is responsible for one or more other tasks within the vehicle. The controller may form part of an electronic vehicle management system incorporating the control system 100 and / or communicate with the control system 100 as is shown in Figure 2. The controller 30 may include and / or communicate with other processors, sensors and outputs, as known to the skilled person and / or from WO2018130378A1. The vehicle 1 may have an automatic transmission and a number of drive modes, including a park mode (‘P’), a reverse mode (‘R’), a neutral mode (‘N’) and a forward (“drive”) mode (‘D’). The vehicle 1 may have additional drive modes as is known in the art, such as a sport mode ‘S’ or manual mode ‘M’. In the reverse mode R, the 35 driven wheels 34 (either front or rear axle for two-wheel drive or both front and rear axle for four-wheel drive) drive the car 100 rearwardly when the park brake and foot brake (not shown) are disengaged and the accelerator (not shown) is depressed. In the drive mode D, the wheels 34 (either front or rear axle for two- 16 09 25 wheel drive or both front and rear axle for four-wheel drive) move the vehicle 1 forwards when a park brake and foot brake are disengaged and an accelerator pedal is depressed. Selection of the drive mode of the automatic transmission conventionally involves moving the drive mode selector 70 between positions representing each of the various modes. A typical sequence (from forward / top 5 to rear / bottom for a lever or clockwise for a rotary selector) is P, R, N, D. In view of the above description of the vehicle 1, it will be understood that the vehicle 1 may be a full hybrid electric vehicle (HEV) ora battery electric vehicle (BEV), a plug-in electric hybrid vehicle (PHEV), a mild hybrid electric vehicle (MHEV), an internal combustion engine vehicle (ICEV) or otherwise. It is envisioned that the present invention may work with any of these vehicle types. 10 BEVs are an electric-only vehicle 1 which are propelled by an electric machine 26 that receives power from an on-board traction battery. The BEV may comprise a single electric machine, or both a first electric machine 26 and a second electric machine 26. The first and second electric machines 26 may provide power to the front and rear axles respectively. Alternatively, the BEV may have an electric machine 26 used to drive each wheel individually, as such a vehicle comprising four wheels may comprise four electric machines 26 with each 15 electric machine driving a single wheel. MHEVs do not have an electric-only mode of propulsion, but the electric machine 26 may be configured to provide assistance such as boosting output torque of the engine 24. In such vehicles the electric machine 26 is not sufficiently powerful to drive the vehicle 1 under electric power alone. ICEV are propelled solely by an engine 24. Any on-board electric machine is used only as a startergenerator. The vehicle 1 may be operable in a single pedal operating mode. The single pedal driving mode may be selected by the driver of the vehicle 1 via a setting on a graphical user interface or a push-button near the steering wheel, or alternatively the single pedal driving mode may be permanently on. The single pedal operating mode enables the vehicle 1 to be driven using the accelerator pedal with braking provided by the braking system, for example by one or more regenerative brakes 62, when the driver lifts pressure from the 25 accelerator pedal. Additional braking may be provided by the driver actuating the brake pedal. In the single pedal driving mode, the regenerative braking enables the vehicle to slow down more quickly when the driver reduces or removes any actuation on the accelerator pedal. The regenerative brakes 62 provide a braking force to arrest or slow movement of the vehicle 1 without the need for the driver to actuate the brake pedal. At the same time, the regenerative braking enables the generation of electrical energy to charge the traction 30 battery. The control system 100 will now be described with the aid of Figures 3 to 7. The control system 100 is illustrated in Figure 3 as comprising one controller 110, although it will be appreciated that this is merely illustrative. The controller 110 comprises processing means 120 and memory means 130. 35 The processing means 120 may be one or more electronic processing device 120 which operably executes computer-readable instructions. The memory means 130 may be one or more memory device 130. The memory means 130 is electrically coupled to the processing means 120. The memory means 130 is configured 16 09^5 to store instructions, and the processing means 120 is configured to access the memory means 130 and execute the instructions stored thereon. The controller 110 comprises an input means 140 and an output means 150. The input means 140 may 5 comprise an electrical input 140 of the controller 110. The output means 150 may comprise an electrical output of the controller 110 to output a control signal 155. The control system 100 is configured to receive, at least one input parameter 310 from a drive mode selector sensor 74, which indicates a selected drive mode of the vehicle, and determine, if a condition is satisfied. If the condition is satisfied the control system 100 then outputs a control signal 155. The input 140 is arranged to receive the at least one input parameter 310 and determine 10 if the condition is satisfied. Then the controller 110 outputs the control signal 155, being a braking torque request signal 330 to the braking system 60 of the vehicle to request a braking torque. The at least one input parameter signal 310 is an electrical signal which is indicative of at least one input parameter. Figure 4 illustrates a flow chart 400 of control system logic carried out by the control system 100, the controller 15 110 and / or processor(s) 120. The flow chart 400 describes control system logic for control of a braking system 60 of a vehicle, such as the vehicle 1 illustrated in Figures 1 and 2. The flow chart 400 concerns the determination of a selection of the neutral drive mode and, in response, application of a braking torque to arrest or slow movement of the vehicle 1. The flow chart 400 comprises a step S410 whereby the at least one input parameter 310 is received by the processor(s) 120. The input parameter 310 comprises the drive mode signal 320. The drive mode signal 320 indicates the selected drive mode of the vehicle 1. Subsequently, at step S420, the selected drive mode is determined in dependence upon the drive mode signal 320. Then, at step S430, represented by a decision box two branches (a ‘1’ branch and a ‘0’ branch) the processor(s) 120 identify if the condition has been 25 satisfied. The condition is satisfied when the selected drive mode is a neutral drive mode N. If the condition is satisfied, then the flow chart 400 will move down the ‘1’ branch to step S450 and output a braking torque request signal 330 to the braking system 60 to request a braking torque from the braking system 60. If the condition is not satisfied, because the neutral drive mode N was not selected, then the flow chart 400 will move to step S440 and end the control system logic. 30 The flow chart 400 and control system logic therein may become active each time a drive mode signal 320 indicates that a drive mode change has been requested. As such, each time the driver requests a drive mode change the control system 100 may check to see if the condition is met. 35 Additionally, or optionally, the processors) 120 are collectively configured to modify the braking torque request signal 330 to increase the braking torque from the braking system 60 during a taper on period. The ability to increase the torque requested over a taper on period prevents a step change in torque application from the braking system which may cause a driveline disturbance felt by the driver of the vehicle. The taper on period may be between: 0.1 seconds and 3.0 seconds, or 0.1 seconds and 2.0 seconds, or 0.5 seconds and 2.0 40 seconds. Alternatively, the taper on period is 1.5 seconds. 16 09^5 Additionally, or optionally, the condition may comprise one or more operating requirements to be satisfied prior to intervention by the control system 100. In such a case, the input parameters further include a vehicle speed signal 322 indicative of a vehicle speed. The processor(s) 120 further include the step of comparing the vehicle speed with one or more thresholds as part of step S420. The condition requires the additional identification at 5 S420 that the vehicle speed is above a minimum speed threshold and / or the vehicle speed is below a maximum speed threshold. Should the condition be met then the control system logic follows the normal route per step S430 discussed above. The minimum speed threshold is 0 kph, 1 kph, 2 kph or 3 kph, or 0 to 3 kph, or any subset or range thereof. 10 Where the speed of the vehicle 1 is below or equal to the speed threshold the condition is not met and the braking torque is not requested. The maximum speed threshold is 20 to 60 kph, or 20 kph, or 30 kph, or 40 kph or 50 kph, or 60 kph, or any subset or range thereof. Where the speed is above the second speed threshold the condition is not met and 15 the braking torque is not requested. In cases where the vehicle 1 is travelling at a speed above or equal to the threshold the vehicle 1 may be being towed, in such cases it would be beneficial to not apply the braking torque above the second speed threshold. Additionally, or optionally, the condition may comprise one or more operating requirements to be satisfied prior to intervention by the control system 100. In such a case, the input parameters 310 further include a gradient signal 324 indicative of a gradient of a surface on which the vehicle is travelling. The processor(s) 120 further include the identifying whether a magnitude of a gradient of the surface on which the vehicle is travelling is greater than a gradient threshold as part of step S420. Should the condition be met then the control system logic follows the normal route per step S430 discussed above. 25 The gradient threshold is: 5%, or 4%, or 3, or 2%, or 1%. Additionally, or optionally, where the input parameters further include one or both of the vehicle speed signal 322 indicative of a vehicle speed and the gradient signal 324 indicative of a gradient of a surface on which the 30 vehicle is travelling the braking torque demanded is dependent upon one or both of the vehicle speed or gradient. Figure 5 illustrates a flow chart 500 having the additional or optional control system logic to flow chart 400 carried out by the control system 100, the controller 110 and / or processor(s) 120. The flow chart 500 describes control system logic for control of a braking system 60 of a vehicle 1 whereby the braking torque requested by the braking torque request signal 330 and is a torque demand Pd. The torque demand Pd is 35 dependent upon one or both of the vehicle speed and the gradient of the surface on which the vehicle is travelling. The flow chart 500 concerns the determination of a torque demand Pd which is tailored to react to current vehicle 1 conditions. The flow chart 500 comprises an additional step S510 between step S430 and S450. At this step the 40 processor(s) 120 determine, independence upon one or both of the vehicle speed and / or the gradient of the 16 09^5 surface on which the vehicle 1 is travelling, a torque demand Pd. The torque demand Pd is then output with the braking torque request signal 330. The torque demand Pd may be calculated by the processor(s) 120 enabling the vehicle 1 to adapt quickly to 5 changing surface conditions or vehicle speeds. In such a case, the torque demand Pd may linearly vary in relation to one, or both, of the vehicle speed and the gradient of the surface on which the vehicle is travelling. Alternatively, or optionally, the torque demand Pd may be obtained from a look-up table. The look-up table comprising a plurality of vehicle speed-gradient pairings. The vehicle speed-torque pairings all indicating a 10 torque demand Pd to be utilised for a particular vehicle speed-torque pairing. The process(s) 120 can access the look-up table which is stored in the memory to select an appropriate torque demand Pd for current driving conditions. An additional, or optional, flow chart 600 is provided in Figure 6. Flow chart 600 provides additional steps in 15 relation to flow chart 500 to modify the braking torque where the condition is no longer satisfied. The advantage of which is to prevent braking where it is no longer required by the control system 100. Flow chart 600 comprises additional steps S610 and S620 which come after step S450. After the braking torque request signal 330 is output at S450 the processor(s) 120 continue to monitor the input parameters 310 to check whether the condition is still met at step S610. For example, if the drive mode signal 320 changes from neutral N to a forward drive mode D then the condition is no longer met. As a result, the braking torque previously requested is no longer required. The control system logic may remain at step S610 until such a time that the condition is no longer met, or alternatively an overriding control system overrides the control system logic of flow chart 600, for example where the vehicle is switched off or a parking brake is applied this may 25 provide a brake condition to stop flow chart 600 or cause it to move onto step S620. After the condition is determined to no longer to be required, then the flow chart 600 moves onto step S620. At step S620 the braking torque request signal 330 is stopped to remove the braking torque requested from the braking system 60. 30 Alternatively, following step S610 where the condition is no longer met the braking torque request signal 330 is modified to reduce the requested braking torque at step S620. For example, the requested braking torque may be modified in dependence upon the vehicle speed and / or gradient on which the vehicle 1 is currently travelling. Alternatively, the modification to the braking torque is determined by providing a look-up table of 35 modified torque demands paired with vehicle speeds and gradients the control system can quickly find the required modified torque to be utilised. Different modified torque demand values can be provided for a number of different values of vehicle speed or vehicle gradient enabling greater control of the braking potential of the vehicle for different driving scenarios. The reduced braking torque requested from the braking system may be pre-calibrated. 40 16 09^5 Alternatively, at step S620 the braking torque may be reduced as part of a taper-off period. The taper-off period is substantially similar to the taper-on period described above however a reduction in braking torque to zero rather than an increase in braking torque from zero per the taper-on period. 5 Optionally, according to any of the flow charts 400, 500, 600 an additional step may be provided whereby the at least one input parameter 310 further comprises a vehicle operating mode signal indicative of a current operating mode of the vehicle. The condition further requires identifying that the current operating mode corresponds to one or more of a set of predefined vehicle operating modes. This enables the control system to output the braking torque request only when the vehicle is operated in certain vehicle operating modes and 10 to avoid requesting braking torque in other vehicle operating modes. This can help to avoid the braking torque being applied when the vehicle is in a vehicle operating mode in which braking is not desired, such as when the vehicle is being towed (in a ‘tow-mode’) or moving through a car wash, for example. The set of predefined vehicle operating modes may include a single pedal operating mode in which acceleration and braking functions are requested through a single pedal, typically the accelerator or gas pedal. Optionally, or additionally the condition comprises a driver detection signal as the vehicle operating mode signal. The driver detection signal is generated when the control system 100 or an alternative control system detects that a driver is present and seated in the driver seat. The detection of driver presence and the generation and output of a driver detection signal to the control system may be made by any one or more of: detecting that the driver side door has been opened and closed in dependence upon a driver side door sensor, that the driver seat belt is buckled in dependence upon a driver seatbelt buckle sensor, a weight is present in the driver seat in dependence upon a driver seat weight sensor. Figures 4 to 6 show flow charts 400, 500, 600 which indicate methods for controlling a braking system 60 of a 25 vehicle 1 according to an embodiment of the invention. The methods of flow charts 400, 500, 600 may be performed by the braking system 60 and control system 100 illustrated in Figure 2 for vehicle 1. In particular, the memory 130 may comprise computer-readable instructions which, when executed by the processor 120, perform the steps of flow charts 400, 500, 600 according to an embodiment of the invention. 30 The method of applying and removing the braking torque as discussed above will be described with the aid of Figure 7 showing a graph 700. Figure 7 has time, t, on the x-axis and braking torque, Pd on the y-axis. ti coincides, or is shortly after, the output step S430. That is, once the condition has been satisfied and the braking torque request signal 330 has been sent to the braking system 60. At ti the braking torque begins to 35 be applied by the braking system 60 until a maximum is reached at t2 as shown by the two curves 710 and 720. The braking torque may either increase at a constant rate, as indicated by the linear curve 710 or the rate of braking torque may change during the taper-on period as indicated by curve 720. Alternatively, instead of a gradual increase the braking torque may be applied as a step change, that is that the requested torque may be a request for a first torque level without any taper-on as indicated in Figure 7 by curves 710 and 720. The torque level reached at time t2 may be dependent upon one or both of the gradient and vehicle speed as discussed above. After time t2 and up to time ta, the braking torque may be maintained on for a time period equal to the difference 5 between t2 and ta. This time period may be 1 to 10 seconds or the time period may last until the condition is no longer satisfied as discussed above with relation to flow chart 600. Whilst the time period t2 to ta is shown as a constant braking torque level, it will be appreciated that the torque level may vary in dependence upon the vehicle speed and / or gradient of the surface on which the vehicle 1 is 10 travelling as discussed above. Subsequently at ta a taper-off period may begin whereby the baking torque request signal is modified or stopped to reduce or stop the braking torque requested from the braking system 60 as discussed above with respect to flow chart 600. Alternatively, instead of a gradual decrease, or decrease in dependence upon vehicle 15 speed and / or gradient, the braking torque may be removed as a step change, that is that the modified torque request may be a request for a zero braking torque level without any taper-off as in curves 710 and 720. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. 16 09^5

Claims

16 09^51. A control system for controlling a braking system of a vehicle, the control system comprising one or more processors collectively configured to:5 receive at least one input parameter comprising:a drive mode signal indicating a selected drive mode of the vehicle;in dependence on the at least one input parameter, identify if a condition is satisfied, wherein the condition requires at least that:the selected drive mode is a neutral drive mode; and10 in response to identifying that the condition is satisfied:output a braking torque request signal for the braking system to request a braking torque from the braking system; andmodify the braking torque request signal to increase the braking torque from the braking system during a taper-on period.

152. The control system of claim 1, wherein the taper-on period is between 0.1 seconds and 3.0 seconds.

3. The control system of any preceding claim, wherein the at least one input parameter further includesa vehicle speed signal indicative of a vehicle speed and / or a gradient signal indicative of a gradient of a surface on which the vehicle is supported.

4. The control system of claim 3, wherein the condition further requires one or more of: that the vehicle speed is above a minimum speed threshold;that the vehicle speed is below a maximum speed threshold; and25 that the gradient of the surface on which the vehicle is supported has a magnitude which isgreater than a gradient threshold.

5. The control system of claim 4, wherein the condition requires that the vehicle speed is above the minimum speed threshold, and wherein the minimum speed threshold is zero.

306. The control system of claim 4 or 5, wherein the condition requires that the vehicle speed is below the maximum speed threshold, and wherein the maximum speed threshold is 20 to 60 kph.

7. The control system of any of claims 4 to 6, wherein the condition requires that the gradient of the 35 surface on which the vehicle is supported has a magnitude which is greater than a gradient threshold, and wherein the gradient threshold is 1%.

8. The control system of any of claims 3 to 7, wherein:the braking torque request signal comprises a braking torque demand indicative of the braking torque 40 requested from the braking system; and16 09^5wherein the braking torque demand is dependent upon at least one of the vehicle speed and the gradient of the surface on which the vehicle is supported.

9. The control system of claim 8, wherein, the braking torque demand varies linearly in relation to one 5 or both of the vehicle speed and the gradient of the surface on which the vehicle is supported.

10. The control system of claim 8 or claim 9, wherein the one or more processors are collectively configured to, in response to identifying that the condition is no longer satisfied, modify the braking torque request signal to reduce the braking torque requested from the braking system.1011. The control system of any preceding claim, wherein the one or more processors are collectively configured to, in response to identifying that the condition is no longer satisfied, modify or stop the braking torque request signal to reduce or stop the braking torque requested from the braking system.15 12. A vehicle comprising the control system of any of claims 1 to 11.

13. A method for controlling a braking system of a vehicle, the method comprising:receiving at least one input parameter comprising:a drive mode signal indicating a selected drive mode of the vehicle;in dependence on the at least one input parameter, identifying if a condition is satisfied, wherein the condition requires at least that:the selected drive mode is a neutral drive mode; andin response to identifying that the condition is satisfied:output a braking torque request signal for the braking system to request a25 braking torque from the braking system; andmodify the braking torque request signal to increase the braking torque from the braking system during a taper-on period.

14. Computer readable instructions which, when executed by a computer, are arranged to perform a 30 method according to claim 13.

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